Scripting material files .armaterial

I need to build materials files from scripts and I did not found any way for .armaterial.
Rhino materials files .rmtl are XML files which can be built from scripts.
Where is it possible to find a file format description for .armaterial files (used by FlamingoNXT) or a tool to convert them from an XML format ?

Any hint or information about this topic will be helpful.
Many thanks !